In Spain, the first paper on fuzzy set theory was published by Trillas and Riera (1978). From 1978 to the present, more than 1,500 papers on the topic have been published by the Spanish fuzzy set research community, as shown by the ISI Web of Science. The Spanish fuzzy set community ranks seventh in the “top-ten” ranking of the most productive countries on fuzzy set theory research, and it is the second European country (according to data from ISI Web of Science).